Phase correction in synchronous telegraph systems



. 1,636,784 y 259 1927' PARKER ET AL PHASE CORRECTION IN SYNCHRONOUSTELEGRAPH SYSTEMS Filed Jan. 6, 1926 Lll Q Q Q I m u o illllllllllI"|Illlllll"llllmllllmll a Z 0 E 3 u; E E '5 0 a: Q o 5 Q E Fk a: Q 2 P m w o 8 Q I 2 Zwwvntow Z. 1 Fania/- l B. Baawaka [I PatentedJuly 26, 1927.

UNITED STATES PATENT OFFICE.

LnrcHLANn F. PARKER,- or BURLINGTON, VERMONT, AND FAY .B. BRAMHALL, or

METUCHEN, NEW JERSEY, ASSIGNORS TO THE WESTERN UNION TELEGRAPH COM-PANY, OF NEW YORK, N. Y., A CORPORATIONOF NEW YORK.

IEHASE CORRECTION IN SYNCHRONOUS TELEGRAPH SYSTEMS.

Application filed January Ourinvention relates to phase correctionAnother object of our invention is to pro vide means requiring nomaintenance for keeping two members in phase.

Still another object of our invention is to provide means for replacinga relay by a condenser to maintain two members in phase.

There are otherobjects of our invention which with the foregoing willbecome apparent.

Telegraph systems such as that herein illustrated and described,compriserotating distributors remotely disposed with respect to eachother, and connected by a signalling conductor. The segments of thedistributors at one end of the conductor are connected to transmittercontacts and at the other end the distributor segments are connectedtorelays :0 of an automatic telegraph printer.

A uniform five unit code known as Baudot code and comprisingcombinations of posi-' tive and negative impulses is used. As thedistributor brush rotates over the segments, 5 a code of five impulsesis transmitted, the

position of the five transmitter contacts de-- termining the polarity ofthese implses. At the receiver these impulses are distributed to -fivereceiving relays as the brush thereat 0 rotates over the segments.

' By this well-known use of the distributor, each transmitter contact isin succession brought into electrical connection with its associatedreceiving relay over a single line 5 and this principle can, of course,as illustrated in the drawing be extended to multiplexing, using each.group of five segments per channel.

It is obvious, however, that for correct 0 operation, the twodistributors must be maintained in synchronism and in phase. Otherwisethe transmitter contact wil1 be connected to the wrong relay over theline resulting in a: false signal.

6, 1926. Serial No. 79,586.

It has been found best in practice to rotate oneof these 'twodistributors slightly faster than the other and then provide means forrestoring the phase relation of the two distributors whenever they fallout a predetermined degree. Heretoforethis means has been a relay, asillustrated in the patent to Rothermel', No. 1,253,889, of which this isan improvement.

The relay R in Rothermel, however, re-

' quires very delicate adjustment and considerable maintenance. Sincethe distributors are rotating at comparative high speed the circuitclosing must be timed just right and always occur at the same time. Arelay is not constant in operation; its moment of contacts shiftscontinuously due to changes in residual magnetisms and the naturalperiod of the armature at certain frequencies. Relays in general aresubjected to the usual mechanical difliculties which make their.

elimination in systems desirable.

In practiclng ourlnventlon, we provide an all electrical means, namely acondenser 'to operate the phase correcting'circuits, so

redesigning these circuits as to make this possible.

Referring now to the drawings, Figure 1 shows the circuits of amultiplex telegraph system embodying our invention.

Fig. 2 illustrates the electrical effects with the brushes of thedistributors in three conditions, namely, in phase, partially out ofphase and entirely out of phase.

Referring first to Fig. 1: D and D designate rotary distributers orcommutators of the general Baudot type, located at opposite ends of aline wire L. Such distributors comprise a plurality of commutator ringsalternate rings being plain and se mented respectively, and suitablebrushes being provide'd for connecting each plain ring elec tricallywith its corresponding segmented ring. Corresponding rings of the twodistributors shown are designated by the same reference characters, viz,S RG S RG S RG and S, RG4; and the brushes are designated by charactersBB BR, BR and BB. A

The distributors shown in Fig. '1 are adapted each for four channels ofcommunication; but for simplicity we have shown transmitting andreceiving means for one channel of communication only in each directionThe distributer rings are shown developed, and we have shown no meansfor driving'the brushes, the mounting of the brushes with reference tothe va rious distributer rings and the methods of rotating such brushes,being well known and disclosed in thepatent to Yorke and Benjamin, No.1,298,622.

T and T designate automatic transmit ters, one at each end of the lineand each adapted to transmit, through its correspond- I mg distributer,to receiving apparatus R brushes of each distributer are mounted upon arotatable-shaft, driven by a motor of very constant speed, the brushshaft of one dist'ributer being usually driven at a normal speed veryslightly greater or very shghtly less, as preferred, than the brushshaft of the other distributer; and the function of I or more of suchreversals, one d-istributer is. sufliciently out of phase withrespecttothe.

the corrector is to step back or to step forward, as the case may be,the brushes of the one distributer with reference to the brush shaft ofthat distributer, in order to restore proper phase relation between thetwo distributers when such restoration is necessary,

The distributer provided with such-correction mechanism is termed thecorrected distributer, while the other distributer, which commonly hasnocorrection mechanism, is termed the correcting distributer. In Fig. 1,,D is the correcting dist-ributer and D is the corrected distributer,correcting mechanism being shown only in connection with distributer DCommonly, a line relay is interposed between each distributer and theline, and commonly the corrected distributer is provided with acorrecting relay in the main line, by which correcting relay thecorrection mechanism of that distributer is directly controlled. In Fig.1, ML designates the two mainline relays, and CL the correcting relayemployed in connection with distributer D According to the YorkeBenjamin correction method, each current reversal afle'cting thecorrecting relay CL affords an opportunity for correction; but thecorrection mechanism operates only when, at the time of one otherdistributer, to requiregcorrectiom'.

In considering the operation of proved corrector,

segments of rings S of distributor D, and

. T- t M-a we-. will consider thattjele graphic characters arebeingtransmitted.

fromdistributer D to vdistri will be noted that contacts of transmitter,T are connected by. suitable conductors to five' that, supposing variouscontact combinations to be set up in transmitter T, when brushconnected, corresponding current impulses will pass through the lefthand mainline relay ML through line wire L and then through the righthand main line relay ML, and relay CL, to ground or other return.Signals from distributor D repeated by the right hand relay ML, passthrough local line Wire L into ring RG of distributer D and thence,through brush BB of that distributer, into ring 8, and so into signal re ceiv ing device R. It is not thought necessary to describe in detailthis signal receiving device; or the method of its operation.

Ring S consists of segments, alternate ones of which are connected torelay R over conductor 6 and negative battery over resistance R; v

The armature of relay CL vibrates, as stated above, in unison with thevibration of the armature of the right hand'relay ML.

If the received impulse is of such a nature as to move to close its lefthand contact, any charge in condenser C will be dissipated over "theresistance It and the armature contacts of relay CL.

If now the line current polarity isu'eversed, the armature of relay CLwill move to'close its right hand contact. If the distributers are inphase at this instant, the brush BB should be on one of the contacts Z)and the condenser C will be charged over a circuit from positive batterycondenser C, armature CL and its right hand contact,

conductor 5', ring RG brush BB segment I), resistance R to negativebattery at 4. As a result, nothing will happen and condenser C will bedischarged upon some subsequent reversal of current as heretoforedescribed.

If the distributors are not in phase at the instant the armature ofrelay CL closes its right hand contact, brush BR will be on one of thesegments a. As a result, a circuit 'willbe completed,- from positivebattery at 1, condenser C, armature of relay CL and its ri ht handcontact, conductor 5, rin

RG' and 6, winding of re ay- R to negative battei'y at 3. Relay R isenergizedover this circuit and closes its armature contact.

As a result of this'a locking circuit for .relay R andenergizingcircuits fer -relay- -R and magnet M are completed. The look ing circuitfor relay R extends from negase retary, winding of relay R conductorfl3', resl stance 12 contact and armature of relay Rfzto positlvebattery at 9. A parallel circuit for energizing relay R is alsocornpleted from negative battery at'3. winding of relay-B,- contactandarmature of relay R to positive batterv -at 9-. The energizingcircuit for magnet M iscompleted from rush BR, segment a, conductorsnegative battery at 11, conductor '10, winding of magnet M, conductor10, contact and armature of relay R to positive battery at 9. 7

Relay R and magnet M are designed as quick-to-operate relays while relayR has a slower charact-eristic.- As a result, both relay R and magnet Mwill have been completely energized before the armature of lay R closesits front contact. The energization of magnet M operates the pawlthrough its armature rotating the ratche wheel one step and brings thetwo distributers back into phase.

Relay R now closes the front contact-of its armature and as a result.shunts the energizing circuit of the relay R from negative battery at 3,armature of relay R" and its front contact, conductor 16 to 13.

As a result of this shunt path, relay R is deenergized and opens itslocking circuit. The'energizing circuits of relay R" and magnet M arealso opened at the armature contact of relay R An analysis of the actionis given in Figure 2 which shows the theoretical received wave, therelative position of the correcting segments and the condenserchargii'ig impulses. It should be noted that the time taken to traversetwo correcting segments is slightly less than the length of one.received impulse. This condition exists when the receiving distributorruns slightly faster than the sending distributer and the mechanicalcorrector steps the brushes backward.

Figure 2 shows the action at various brush positions. A shows the actiondirectly following a correction when the correcting brush is on a 1)segment at the moment of current reversal. In this case as the tongue ofthe corrector relay touches its marking contact the condenser charge isentirely wasted through the resistance R At position B the brushes ofdistributer D have advanced slightly due to their greater speed and inthis case the greater part of the condenser charge is through resistanceR and the remainder through the make relay. This small current throughthe make relay is not suflicient to operate it and the brushes continueto advance with respect to the received wave. At C a greater-portion ofthe charge current passes through the make relay'but still not' enoughto operate it. At D, however, the full charge currentpasses through the.a segment and the make relay is operated; This in turn operatesthemechanical c'orrector and the brushes'are stepped back to the positionshown at A and the'process is repeated synchronism with the receivedwave.

From this analysis, the importance of rei placing the relay disclosed inRothermel, by a condenser is evident. By using the condenser, a singleinstantaneous current surge is obtained. The period and measure of thissurge can be definitely predetermined by condenser design. Thesclectedconstants \Vlll depend on the speed of the distributer and the size ofsegments also estimated than the received wave and the brushes arestepped ahead.

Although we have disclosed our invention in connection with a multiplextelegraph system, it is understood, of course, that it has more generalapplication as, for example, where continuously operating synchronouscommutators or distribnters are employed in a live circuit andapplicants do not intend to limit themselves to thespeeific embodimentdisclosed but only so far as set forth in the claims which follow.

\Ve claim as our invention:

1. In a telegraph system, a correcting distributer, a correcteddistributer rotating in approxin'iate synchronism with said correctingdistributer, a circuit connecting said distributers, means fortransmitting impulses oftwo polarities over said circuit, a condenser: aphase correcting relay, mechanism controlled by said relay to shift thebrushes of the distributor relative to their driving shaft, circuitarrangements wherebysaid condenser is charged on each reversal ofpolarity of said impulses and second circuit arrangements whereby saidcharging impulse also operates-said phase correcting relay.

2. The method of phase correction between 'two members rotating inapproximate synchronism which comprises reversing the polarity ofimpulses periodically, producing by said reversals a surge when saidmembers are out of phase and operating a correcting mechanism with saidsurge to shift the brushes of onemember relative to their driving shaft.7 i

3. In a telegraph system, a correcting distributer, acorrected'distributer rotating in approximate synchronism with saidcorrecting distributer', a circuit connecting said distributers, meansfor. transmitting impulses of two polarities over said circuit,electrostatic means, a phase correcting relay, mechanism controlled byvsaid relay to shift the brushes of the. distributor relative to theirdriving shaft, circuit arrangements whereby said condenser is charged oneach reversal izo of polarityof said impulses and second circuitarrangements whereby said charging imlpulse also operates said phasecorrecting re a I 4., The method of phase correction between impulsesand a distributer which comprises producing surges by said impulses andoperating -a phase corrector by said surges to shift the distributorbrushes relative to their driving shaft. y

5.-In combination, a correcting member, a corrected member, anelectrical circuit connecting said members, means for transmittingimpulses of two characteristics over said circuit, a condenser, circuitarrangement whereby said condenser is charged by a change of saidreceived impulses, a correcting relay, mechanism controlled by saidrelay to shift the brushes of the distributor relative totheir drivingshaft, and circuit arrangements whereby said condenser dis chargesthrough said relay only when said distributers are out of phase.

In testimony whereof, we aifix our signatures.

LEIGHLAND F. PARKER. FAY B. BRAMHALL.

